12 2026 02 12 Crestmont CC Stormwater Management Report

Project: Eagle Rock Avenue By: TEG Date: 10/21/2025 Location: West Orange, NJ Checked By: MJV Date Checked: 10/21/2025 Circle One: Present Developed Current Proposed Watershed PR-1C-D - Pervious Circle One: Tc Tt through subarea Include a map, schematic, or description of flow segments. Sheet Flow (Applicable to Tc Only) Segment ID 1 Dense Grasses 1. Surface Description (NEH table 15-1) 2. Manning's Roughness Coeff., n (NEH table 15-1) 0.24 3. Design Flow Length, Ldes (Total Ldes < 100 ft) ft 54 4. Two-year 24-hr rainfall, P2 in 3.46 5. Land Slope, s ft/ft 0.212 6. McCuen-Spiess Limit, Lmcs (max. 100 ft) Lmcs = (100 s0.5)/n ft 100 7. Compute Tt 0.007 (nLdes)0.8 hr 0.054 + + Tt = 0.5 0.4 P2 s Sheet Flow Sub-Total 0.054 hours Shallow Concentrated Flow Segment ID 8. Surface Description 9. Flow Length, L ft 10. Watercourse Slope, s ft/ft 11. Average Velocity, V (NEH table 15-3) ft/s 12. Compute Tt L hr + + Tt = 3600 V

+ Tt = 3600 V Shallow Conc. Flow Sub-Total 0.000 hours Channel Flow Segment ID 2 3 4 13. Flow Length, L ft 17 51 67 14. Cross Sectional flow area, a ft2 0.88 0.88 0.88 15. Wetted Perimeter, Pw ft 2.40 2.40 2.40 16. Hydraulic Radius, r r = a / Pw ft 0.37 0.37 0.37 17. Channel Slope, s ft/ft 0.049 0.021 0.042 18. Manning's Roughness Coeff., n 0.013 0.013 0.013 19. Velocity, V V = (1.49 r2/3 s1/2 ) / n ft/s 13.05 8.54 11.98 20. Compute Tt L hr 0.000 + 0.002 + 0.002 Tt = 3600 V Channel Flow Sub-Total 0.004 hours Watershed or subarea Tc or Tt Total Tc (hours) = 0.058 hours (Add Sub-Total Tt from prior steps) Total Tc (minutes) = 3 minutes \\langan.com\data\PAR\data8\101049801\Project Data\_Discipline\Site Civil\Stormwater\Time of Concentration Calcs\Proposed Tc Calcs\Current Proposed TCs\Current Proposed TC PR-1C-D Pervious

utes \\langan.com\data\PAR\data8\101049801\Project Data\_Discipline\Site Civil\Stormwater\Time of Concentration Calcs\Proposed Tc Calcs\Current Proposed TCs\Current Proposed TC PR-1C-D Pervious v1.4